测绘专业毕业设计中英文文献GIS

测绘专业毕业设计中英文文献GIS
测绘专业毕业设计中英文文献GIS

Definitions of GIS

“GIS” is an acronym meaning of Geographic Information System. In order to provide a good understanding of GIS, the following two definitions given by R hind (1989) and the United

States Geological Survey (USGS, 1997) respectively are presented first.

1 “a system of hard w are, software, a n d procedures designed to support the capture, management, manipulation , analysis, modeling, and display of spatially referenced data for solving complex planning an d management problems .”

2 “a co mputer system capable of assembling , storing, manipulating, and displaying geographically referenced information , i.e., data identified according to their location .”

GIS books generally adopt the ideas expressed by these two definitions. These two characteristics distinguish GIS from other types of information systems: The word “Geographic” in GIS explains “spatially” where things are such as the location of nations, states, counties, cities, schools, roads, rivers, lakes, and the list can go on and on. Spatially means where on the earth’s surface an object or feature is located. T his can be as simple as the latitude and longitude of a feature. T he geographic feature or object can be anything of interest

.“ Information” in GIS is the “data” or “attribute” information about specific features that we are interested in. The name of the feature, what the feature is, the location of the feature, and any other information that is important. An example could be the name of a city , w here it is located , ho w big it is in square feet ( area) , its population , its population in the past, and any other information that is important . “System” in GIS is the computer software that is written to help people analyze the data, look at the data and combine

it in various ways to show relationships or to create geographic models .

A GIS can be made up of a variety of software and hardware tools, as long as they are integrated to provide a functional geographic data processing tool.

As mentioned above, GIS is a computer system that links geographic information (where things are) with descriptive information (what things are) . Unlike a flat paper map, w here

“What you see is w hat you get”, a GIS can present m any layers of different information. To use a paper map, all you do is unfold it. Spread

out before you is a representation of cities and roads, mountains and rivers, railroads, and political boundaries. T he cities are represented by little dots or circles, the roads by black lines, the mountain peaks by tiny triangles, and the lakes by s m all blue areas similar to the real lakes . A digital map is not much

more difficult to use than a paper map. As on the paper map, there are dots or points that represent features on the map such as cities, lines that represent features such as roads, and small areas that represent features such as lakes . All this information—where the point is located , how long the road is, and even how many square miles a lake occupies—is stored as layers in digital for m at as a pattern of ones and zeros in a computer . Think of this geographic data as layers of information underneath the computer screen. Each layer represents a particular the m e or feature of the map. O ne the m e could be made up of all the roads in an area. Another me could represent all the lakes in the same area. Yet another could represent all the cities. These themes can be laid on top of one another, creating a stack of information about the same geographic area. E ach layer can be turned off and on, as if you were peeling a layer off the stack or placing it back on. You control the amount of information about an area that you want to see, at anytime, on any specific map. The technology components of a GIS can be explained interims of hard ware, software and human resources. GIS hard ware includes: computers, computer configuration/ net works, input devices, printers, and storage systems. Computers for GIS usage can be P Cs or supercomputers. These computers can be stand-alone units or can be hooked into a network environment. Input devices include digitizers and scanners. Printers and plotters are used to produce a hardcopy map. GIS storage systems include: optical disks, magnetic disks (such as a hard drive), floppy disks or magnetic tapes.

GIS software includes both GIS program and special application packages, such as digital Terrain modeling and network analysis. The main difference between GIS software programs and desktop mapping programs is the ability of GIS programs to perform spatial analysis. ARC/ INFO by Environ mental Systems Research Institute (ESRI) Inc. is one of typical examples of GIS software packages. Desktop mapping programs offer m any of the same features, as a GIS, but their ability to support spatial analyses are limited. They are developed to satisfy individual user needs for mapping presentations. MapInfo developed by MapInfo Corp is an example of popular desktop mapping programs. Human resources used to operate a GIS typically include: operational staff, technical

professional staff, and management personnel Operational staffers people such as (1) cartographers, who monitor the design of map displays, the

standards for map symbols and standard map series, (2) data capturers, who converts map into digital form and (3) potential users

of a GIS . Technical professional staff include (1) information analysts w ho solve particular user problems and satisfy their information needs, (2) system administrators, who are responsible for keeping the system (hardware/ software) operational , (3) programmers, who translate the application specifications prepared by the analyst into programs and (4) the database administrator, w ho assists the analysts, programmers and users to organize geographic features into layers, identify sources of data , develop coding structures for no graphics data, and document information about the contents of the databases . Management personnel include (1 ) the manager, who monitors the daily performance of the GIS project Implementation team and manages the output production as required by the organization and (2) the Quality Assurance Coordinator w ho manages the output of the final product to ensure that it meets the conversion specification and data acceptance plan. H o w a GIS Works:

A GIS works by providing a way to capture or input data , store , retrieve and manage the data , manipulate and analyze the data , and finally a w ay of displaying that data as a map or as a document or both . Let’s take a closer look as each of these aspects of GIS.

Data Input: All GIS data ha s to be in a digital form at so whether it’s a report, a photo, a map, or information gathered in the field , it has to be made digital . Obtaining geographic data to insert into a GIS is a large subject in which includes a number of different approaches. One of the most common ways to collect spatial geographic data is to perform a physical survey. This includes surveying the land, underwater areas, and underground features of the earth (which are referred to as field survey, hydrographic survey and mining survey respectively) .

Basic forms of data input include: (1) Typing: Reports, survey documents,

population statistics, etc., all have to be entered into the computer preferably in a data base for m at or as tabular data . (2) Scanning: Paper maps such as topographic maps, aerial photographs, remotely sensed images if not already in a digital for m at need to be scanned and then georeferenced or georectified. When a picture or a map or an aerial photo is georeferenced it will open in a GIS program in the right place on a map in relation to other map objects being viewed. They will be in the proper place spatially. (3) Digitizing: currently digitizing is the most common method for converting existing maps and images into digital form. Digitizing

is basically tracing points, lines, or areas fro m a paper map , or aerial photo so that instead of a photograph or a raster image , there is no w a digital line graphic or vector file .

(4) GPS data capture: Data can also be placed in a GIS as points, lines, and polygons from a GPS unit if it has the capability of recording such information. (5) Aerial photography/remote sensing: T his is an increasingly popular way to gather spatial data. Aerial photographs are taken fro m an aircraft, after which they are measured and interpreted. Similarly, satellite re mote sensing can be interpreted for physical features and attributes. (6)Censuses: Censuses conducted by the U.S. Census Bureau gather a variety of demographic data such as population , age structure , sex ratio, race co m position , employment rates . (7) Statistics: Statistics are a set of mathematical methods used to collect and analyze data .These methods include the collection and study of data at different time intervals and at a fixed location, providing information for yearbooks, weather station reports, etc. This information often has a spatial component and can thus be incorporated into a GIS. (8) Tracking: Tracking is a process of collecting attribute data on changes that occur at a location over a period of time. Examples of tracking include: monitoring the change of an ecosystem, and real-time monitoring of a moving objects such as vehicles.

Data Storage, Retrieval, and Management: Different types of information required for a GIS require storage which allows the information to be updated and queried for analysis by the user. There are two types of information to be stored; spatial data and attribute data, which is the topic of next text. Data Manipulation and Analysis: A good system and/ or software package allows the user to define and execute spatial and attribute procedures. T his is commonly thought of as the heart of the GIS. Overlaying, buffering, modeling, and analysis are so m e of the methods used in building a coverage or project. It also takes the users knowledge to recognize what is seen in the resulting map and data. The power of GIS is in the analysis of data.

Data Output: Usually this is a map or graphic, which the user has generated after analyzing the data. School districts can use GIS to help the m in decisions like school boundaries and then create a map to distribute to the community. Tabular data and reports can be generated as w ell to help explain the details seen in the map or graphic and ho w the conclusions w ere derived.

地理信息系统基础

GIS定义

GIS是一个只取首字母的地理信息系统意义的缩写词。为了更好的理解GIS,首先给出两个定义,分别是由Rhind(1989)和美国地质勘探局USGS(1997)年提出的。

1. “由硬件、软件和为支持空间数据采集、管理、操作、分析、建模及显示而设计的程序组成,用于解决复杂规划和管理问题的一种系统。”

2. “一种能够采集、存贮、操作并显示地理相关信息,也就是根据位置来数据识别的计算机系统。”

GIS书籍主要采用这两种定义的解释。GIS区别于其它信息系统的两个特征是:GIS中“地理”这个词解释为在“空间上”物体在哪,比如,国家、州、县、城市、学校、道路、河流、湖泊的位置,并且可继续不停的列下去。空间指一个物体或特征在地球表面的何处。这可以是一个特征点的经纬度这样简单。地理特征或地物可以是任何所感兴趣的东西。“信息”,在GIS中是关于我们研究的特征的“数据”或“属性”信息。特征的名称、特征为何物、特征的位置、及其它任何其它重要信息。例如,一座城市的名称、坐落、面积多大、人口、历史人口,及任何其它重要信息。“系统”在GIS中是设计用来辅助人们分析、查看数据并以不同方式组合来显示其关系或建立地理模型的计算机软件。一个GIS 可以由很多软件和硬件工具组成,只要它们融合起来提供一种功能性的地理数据处理工具。

GIS如何工作:

GIS工作是通过提供一种方法来采集或输入、存贮、检索与管理、操作和分析数据并最终以地图或文档或两者皆有的方式显示数据。让我们近距离认识GIS的每一方面。

数据输入:所有GIS数据必须是一种数字化格式,所以不管它是一个报表、一张照片、一幅地图还是野外采集的信息,都要进行数字化。获取用于GIS的地理数据是一项大课题,包括众多不同方法。采集空间地理数据最常用方法之一是进行实地测量。它包括测量地面、地下水区域和地球地面下特征测量(指外业

测量,水文测量和矿山测量)。

输入数据的基本形式包括:(1)打印:报表、测量文档、人口统计等等,所有的都要以一种数据库格式或作为列表数据更好地输入到计算机;(2)扫描:纸质地图,如地形图,航片,遥感影像,如果不是数字化格式,就需要扫描然后地理定位或矫正。当一照片或一地图或航片经过地理定位,它就可以在GIS中打开到相对于其它地图的正确位置。它们在空间上在正确位置。(3)数字化:当前,数字化是将现在地图和影像转换成数字格式最常用的方法。数字化主要是在纸质图或航片上跟踪点、线或面,这样代替一张图片或栅格影像的是一个数字化线图或矢量文件。(4)GPS数据采集,由GPS单元获取的点、线和多边形数据也可以用于GIS,只要GPS有计算这些信息的能力。(5)航空摄影/遥感:这是采集空间数据越来越大众化的方法。航片是由飞行器拍摄并经过测量和解译的。类似

地,卫星遥感也可以解读物理特征和属性。(6)人口普查:由美国人口调查局实施的人口普查采集到大量人口统计学数据,如人口数、年龄结构、性别比率、种族组成、工作比例。(7)统计:统计是一系列用于采集和分析数据的数学方法。(8)追踪调查:是在一个位置一段时间内采集属性数据变化的过程。

数据存贮,检索和管理:

GIS中不同类型的信息要求存贮允许用户信息更新和查询分析。有两种类型数据被存贮:空间数据和属性数据,这是下一课的内容。

数据操作和分析:

一个好的系统或软件包允许用户定义并执行空间和属性处理。这是GIS的基本核心思想。叠加、缓冲区、建模和分析是建立范围和项目的方法。也需要用户的经验来判别成果图和数据中会看到什么。GIS的长处在于数据分析。

数据输出:

通常是地图或图片,这是用户分析数据后生成的。学校管辖区可以用GIS辅助决策,如学校界线,然后建立一幅图分发到公众。可以生成列表数据和报表辅助解释地图或图片中看到的细节和如何得出的结论。

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